Oh well the lander and rover are still alive and working - in fact late on January 22 (UTC) the rover performed direct data exchange to the lander via UHF - the first time two Chinese spacecraft communicate to each other on another planetary body.

...4) I have never heard of a seismic survey instrument being used for seismic monitoring. I don't know if this is even possible, seismic surveys and earthquakes generate signals in quite different frequencies....

Now we have. (12:45 onwards. #TIL Philae's apparently carrying both types of instruments. Electromagnetic wave interrogtion, as well as acoustic.)

...4) I have never heard of a seismic survey instrument being used for seismic monitoring. I don't know if this is even possible, seismic surveys and earthquakes generate signals in quite different frequencies....

Now we have. (12:45 onwards. #TIL Philae's apparently carrying both types of instruments. Electromagnetic wave interrogtion, as well as acoustic.)

ESA commissioned this excellent video explaining how Philae works using lots of Lego:

Thanks for this. Comets are small bodies and the internal seismic events will generate high frequency signals making such an instrument possible.

Seismic monitoring and seismic surveying are on larger bodies require quite different types of instruments. We saw this with Apollo, where the siesmic observatories (PSEP and PSE) were quite different from the active seismic experiments (ASE).

The electromagnetic sounder is a permittivity probe, which is a very arcane device! It measures dielectric constant and conductivity of surface materials and relates it to water content. It also monitors the plasma environment.

Logged

"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

BEIJING, Jan. 25 (Xinhua) -- China's moon rover "Yutu" (Jade Rabbit) has had an abnormity, and scientists are organizing an overhaul, the State Administration of Science, Technology and Industry for National Defence said on Saturday.

I think that "abnormity" should be "anomaly." (They probably meant "abnormality" which is not quite correct.)

BEIJING, Jan. 25 (Xinhua) -- China's moon rover "Yutu" (Jade Rabbit) has had an abnormity, and scientists are organizing an overhaul, the State Administration of Science, Technology and Industry for National Defence said on Saturday.

I think that "abnormity" should be "anomaly." (They probably meant "abnormality" which is not quite correct.)

From what I just saw from Chinese sources, it sounds like if the rover can't flip back the solar arrays inside the body for thermal protection during the lunar night. Big oops if that can't be solved in a few (Earth) day's time....

BEIJING, Jan. 25 (Xinhua) -- China's moon rover "Yutu" (Jade Rabbit) has had a mechanical control abnormity, and scientists are organizing an overhaul.

The abnormity occurred due to "the complicated lunar surface environment," the State Administration of Science, Technology and Industry for National Defence (SASTIND) said on Saturday, without giving further details.

The abnormity emerged before the rover went into its second dormancy at dawn on Saturday as the lunar night fell again, according to the SASTIND.

It seems all the news reports now states yutu has entered sleeping mode and the statement about the malfunction has being stated in the past tense. I think they have found a work around, but is unsure how it will work, so they won't call it a fix yet. hopefully the more detail will emerge tomorrow.

my translationA few days before I was feeling bad, so I didn't update much, and the time we can talk to each other is numbered...... although I often tell you bad jokes, but in fact is really not easy to do lunar explorers. Able to look at the moon, but also to share with you, I've been very happy. In the near future on the moon will drop to minus 180 ℃. I do not know when I can be repaired, so, let me wish you all a Happy New Year in advance!

I'm sorry, everyone is so worry about me ...... masters won't give up treat me, I will not give up easily. Well, for everyone to see articles me. But the master is very shy, embarrassed to tell you who he is (or may be afraid of everyone that he is not well written ......), entrusted to the king to publish a Nutshell. After reading, I think it's horrorible to deconstruct me that......

From the popular theory seems to be the rover had hit some rough patchs, and the structure had some damage causing things to not close properly.

"At least they now have around 14 days or so, to analyse any data on Yutu malfunction and prepare upload commands that may rectify problem or at least provide a workaround."

Alas, no - the problem seems to be that the camera mast and high gain antenna could not be protected from the cold of the lunar night - over the previous night the mast folded back into a box on the rover top and was covered by one solar panel. That closed compartment was warmed by a small radioisotope heat source. The other solar panel was oriented to face the rising sun next morning. This time the mast could fold back but the solar panel could not fold over it to enclose it. So there may be major repercussions from this that 14 days of analysis will not help to resolve.

"At least they now have around 14 days or so, to analyse any data on Yutu malfunction and prepare upload commands that may rectify problem or at least provide a workaround."

Alas, no - the problem seems to be that the camera mast and high gain antenna could not be protected from the cold of the lunar night - over the previous night the mast folded back into a box on the rover top and was covered by one solar panel. That closed compartment was warmed by a small radioisotope heat source. The other solar panel was oriented to face the rising sun next morning. This time the mast could fold back but the solar panel could not fold over it to enclose it. So there may be major repercussions from this that 14 days of analysis will not help to resolve.

Phil

Presumably they will still have low gain comm, and don't they also have small navigation cameras on the base of the rover?

1. How fast does the terminator move across the solar surface - at the Rover's latitude?What's Yutu's top speed?

Why can't they upload a software routine that asks the rover to track, and remain in a zone of optimum temperature (in the vicinity of the terminator) - all the way across the moon?The rover has an TX/RX strong enough to communicate with Earth. So it's not dependent on the lander for this. This also means that it can communicate with LRO/LADEE. There are loads of encoding and modulation strategies that may be employed to get data back. It doesn't have to be bitmap images. Engineering data -- A(x) second long radio burst at frequency B(x) if you've driven C(x) metres in the last D(x) hours -- etc. etc.

Earlier in this (or the discussion thread), we've also spoken about beyond the horizon communication on the moon...using an "ionosphere"... so that may be possible too. Although, with the frequency shift required, it might not be all that much "easier".

Can someone make me feel better and tell me that the bottleneck is sunset speed, and perhaps the terrain, and not the politics?

2. Do they think that rover will freeze irreversibly if the panels don't fold back? Assuming stuff isn't going to literally break/come apart because of differential thermal contraction; that the solar cells (and the computer/software) survive; they should be able to get back to a stable thermal config shortly after sunrise --if they can hardwire "on" the resistive electrical heaters (assuming the rover has any), and the computer to the array outputs, prior to shutdown. Maybe they can introduce a temperature sensor based trigger event to restart the computer? Oh, what they wouldn't give for a space qualified FPGA on the rover right now

EDIT: Ok, it seems, from Blackstar's post that it's only the mast that'll be affected. That's more optimistic than the entire rover. But I am wondering about the RTG heat escaping faster from an unshielded empty box, than a box covered with the panel - cooling the rest of the rover down.

3. I know that without an atmosphere to speak of, it probably won't make much of a difference - but can the rover drive to the lander, and station itself near it, or near a lander heat source? Could it possibly make contact with some part of the lander that can act as a conductive heat source to the rover? The lander doesn't have a lot of spare thermal energy, but I'm wondering if they can operate in the engineering safety-factor zone for both; if they establish a conductive heat path between them.

Also, come to think of it.. if they're sure that rover will be doomed otherwise, can't they command it to drive sideways (array first) against the sloping lander legs, or the engine bells, and force the panels up – and close them? How fragile are the arrays on a typical spacecraft? The fact that you can see standing waves in a video of the panel deployment (CE'2 I think it was) doesn't bode well for this approach.

The idea of keeping ahead of the terminator is a good one, but alas it won't work here. At the equator the terminator moves about 12 degrees per earth day. That's 360 km/day. At this latitude it's still about 250 km/day. Little Yutu can't outpace that, and if it could it would only work until the limb was reached in 6 days.

A related idea was proposed by Red Whittaker and colleagues some years ago. You drive a circle around the pole, far enough out that big areas of shadow are avoided but close enough in that the circle is not too big. To put rough numbers to it, the Moon takes about 700 hours to rotate once, so if you could drive at 1 km/hour you could drive a circle around the pole with a circumference of 700 km. That works out (very roughly again) to a circle at about 83 or 84 degrees north. Whittaker called it a 'Magellan Route', circumnavigating the Moon once per day. That could last for months or years until the rover broke down but it includes far side driving.

EDIT: Ok, it seems, from Blackstar's post that it's only the mast that'll be affected. That's more optimistic than the entire rover.

Note: I have no knowledge of this stuff at all. I'm just speculating. I was pointing out that simply because they could not retract the mast does not mean that the entire rover will die from cold. They could still have other systems alive. And it is possible that they might not lose the mast either. We won't know until the next daytime cycle.